Collision trigger with VuMark

Hello, I'm using Vuforia with VuMark to complete a college work and I'm struggling with collisions.

I want to know if there's a way to make objects collides, for instance, I have 2 spheres that are at position 0,0,0 at the beggining (which is the center of the marker), and I would like to make them collide only when I physically approach both markers, and not to instantly collide as both of them are at the same position, I know this sounds kinda dumb, but I can't have multiple marks at the scene, as I'm working with VuMark and you can have only one (you only print different ones for differents objects, but inside Unity it will be a single one).

Some pictures to let it clear:

Two spheres, 'na' and 'cl', both starts at the default color, and I want to turn them to green when they collide.


Of course, they both instantly collides when the project runs.


I want to know how I could (and if I could) make them collide only when I move them phisically (in real life).

Thanks.